Mesoscale Precipitation Discussion 0617
NWS Weather Prediction Center College Park MD
806 PM EDT Mon Jul 07 2025

Areas affected...Eastern NEB...Western IA...Far Southeast SD...

Concerning...Heavy rainfall...Flash flooding possible

Valid 080005Z - 080600Z

SUMMARY...Merging clusters of severe weather and increasing
mositure flux pose short-term intense bursts of heavy rainfall and
localized totals of 2-3.5" and possible flash flooding.

DISCUSSION...Regional RADAR mosaic and GOES-E Visible imagery show
a large cluster of thunderstorms at the base of northern stream
shortwave trough crossing the Red River of the North where surface
warm front has lifted across the Missouri River Valley slowly
today.  Southerly low level winds of 850mb have been steadily
increasing moisture return with  Tds in the upper 60s and lower
70s.  While mid-level moisture is enahnced across the 700-500mb
layer at this intersection of the northern stream trof and the
returning moisture.  As such, total Pwats are increasing to 1.75"
and strong convective clusters with severe winds/hail are going to
increase in rainfall efficiency over the next few hours.

However, in the short-term some cells that have developed on the
southerly WAA in northeast NEB continue to lift north and will
start to merge with the southeastward cluster. This merger will
rapidly enhanced rainfall rates to over 2"/hr and may slow the
fairly progressive southeastward push of the overall system. 
Isolated spots of 3"/hr while uncommon, may result and may quickly
overwhelm any soil condition; dry/wet or normal.

However, deep layer steering and cold pool generation will quickly
overcome that initial intersection and track/repeat southeastward
likely limiting overall totals thereafter, especially further
north and east within the overall complex.  Though in the wake of
the cluster, low level jet flow will remain out of the south an
increase to 20-25kts and with some further veering may allow for
further isentropic development along the flanking line.  As such,
upwind redevelopment will have the potential for training allowing
for spots of 2-3.5" to occur, likely across northeat NEB just east
of the Sand Hills over areas of FFG values of 1.5-2"/hr and
2-2.5"/3hrs.  As such, incidents of flash flooding may be possible
along the flanking line through the early overnight period toward
06z. 

Gallina

ATTN...WFO...DMX...FSD...GID...OAX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   43519732 43299628 42679539 41899478 41229523
            40909629 40939748 41549807 42519825 43049815